Image processing is often heard of in photography and movies. The scanner is an indispensable part of this technology. Increasing the resolution of the scanner is investigated hard in order to get more clear images, but high cost is not avoidable with high resolution scanners. The operating principle of the conventional scanner is shown in FIG. 1. An article 11 is placed in the scanner to be scanned. The photo-image 12 of the article 11 is focused on a charge coupled device 15 by a lens set 14, and then is converted into electronic signals to form digital information. A mirror set 13 is used for reflecting the light, so the length of the light path does not have to be shortened even though the height of the scanner is reduced. When higher resolution is required, the number of cells for the charge coupled device 15 must be increased. The cost of the charge coupled device 15 is proportional to the square of the number of cells for it. Requiring higher resolution will thus cost much since the cost of a charge coupled device 15 is a great part of the production cost of a scanner. It is clear that high resolution and low cost are difficult to be harmonized according to the stated prior art.
Another prior art has been developed to obviate the trouble of high-cost. Please refer to FIG. 2 showing the working principle of a scanner according to the second prior art. The photo-image 22 of the scanned article 21 is divided into more sections. There are as many corresponding mirror sets 23, lens sets 24, and charge coupled devices 25 as the photo-image sections in this scanner. Different sections of the photo-image 22 are converted into electronic signals via the same steps as the first prior art by respective mirror sets 23, lens sets 24, and charge coupled devices 25. The electronic signals will be combined to form a full image later. Hence, the number of cells for a charge coupled device 25 is reduced, but the performance can be maintained to correspond to that achieved by the prior art with number of cells remained the same. This arrangement can reduce the cost, and the cost is proportional to the number of charge coupled devices 25. However, we still hope to make a big step forward in increasing resolution and decreasing cost.